The subject application relates generally to elevator systems and to brakes for elevator systems, and more particularly to an improved system for braking an elevator. Elevator brakes are used to insure an elevator car stops at the appropriate point and time in the appropriate manner.
Safety regulations concerning the operation of elevators require failsafe brake mechanisms. Typically a plurality of braking mechanisms are provided to hold the elevator car in place when it stops at a landing. The braking mechanisms also serve to stop and stabilize the elevator car during emergency situations such as when there is a system failure, the brake mechanisms must stop the elevator car from uncontrolled travel within the shaft.
Generally, an elevator system comprises a motor, drive shaft and brake system controlling an elevator car within a shaft or hoistway. Traditional techniques for controlling the elevator car also include the use of a counterweight. Several devices have been developed to serve the braking function. Many deployed brake systems apply a frictional force upon the guiderails guiding the elevator car. Such brake systems have deployed a brake surface on one side of the guiderail and a leaf spring and roller assembly on the opposite side of the guiderail. The safety brakes are attached directly to the frame of the elevator car or the counterweight to receive the large load applied in braking thereupon. Alternatively, brake apparatus have utilized drum brakes and disc brakes which engage the drive shaft of the elevator motor. In order to set the gap between the braking surfaces and the guiderails, conventional brakes require a mounting plate and stand-offs.
Many prior art elevator systems located the control system, drive mechanism, brake mechanism, governor and like components outside the hoistway because the bulky machinery had burdensome space and noise requirements. Often, a facilities room had to be built outside the shaft, usually on the roof to accommodate the elevator car arriving at the top landing. A facilities room added additional expense and construction time. Further, the facilities room detrimentally affects the building aesthetics. The position of the brake mechanisms in the facilities room limited the need to require silent operation of the brake mechanisms because the facilities room was remote and muffled most of the potentially disconcerting noises from the passengers. As a result of the size of the facilities room, the size of the brake mechanism was also of reduced importance.
Some examples of elevator brake mechanisms are illustrated in U.S. Pat. No. 5,495,919 to Ericson et al., U.S. Pat. No. 5,669,469 to Ericson et al. U.S. Pat. No. RE36,034 to Sheridan, U.S. Pat. No. 5,717,174 to Ramos, the disclosure of each is herein incorporated by reference to the extent it is consistent with the present application.
In view of the above undesirability of having a facilities room and shortcomings of the prior art, there are problems associated with locating conventional elevator brake mechanisms within the space allotted for the elevator car. In particular, prior art elevator brake mechanism required significant amounts of space. Further, prior art elevator brake mechanisms required redundant systems and performed in an undesirably noisy manner. Therefore, there is a need for an improved elevator brake assembly which fits unobtrusively within the hoistway, performs in a suitably quiet manner relative to passengers in the elevator car, and assures adequate braking performance and redundancy.
The present disclosure provides an elevator car brake having redundancy for parking and holding an elevator motor with an elongated drive shaft. The elevator car brake includes a brake housing for mounting the elevator car brake to the elevator motor. The brake housing has a friction surface. A disc assembly has a body portion adapted and configured to be contained within the housing. The disc assembly is axially fixed with respect to the elongated drive shaft and engaged to rotate therewith. A flange on the disc assembly receives a first ring and a second ring. Each ring is slideably engaged to the flange for motion in an axial direction where the first ring is adjacent to the friction surface of the housing. A first release plate and a second release plate have respective friction surfaces. The first and second release plates are free to move in an axial direction, each release plate being adjacent to the second ring. A fixed field cup combines with the housing to encompass each of the components. The fixed field cup has an adjustment cap for varying the compression of a portion of the plurality of springs and an electromagnetic coil for creating a magnetic field when current flows therethrough. The fixed field cup also has a plurality of springs to bias the first and second release plates against the second ring and a plurality of o-rings in a face of the field cup.
When no current flows through the electromagnetic coil, at least one of the release plates is biased against the second ring. The ability of both release plates to engage the second ring independently creates a desirable redundancy. The second ring translates a force of the plurality of springs to the first ring thereby engaging the friction surface of the housing to park and hold the drive shaft. When current flows through the electromagnetic coil, the first and second release plates are drawn to the face of the field cup, compress the o-rings and are frictionally linked therewith. The o-rings facilitate quiet operation of the elevator car brake.
In another embodiment, a quiet brake assembly is provided for stopping an elongated drive shaft of a motor, including a brake housing having a friction material; a disc assembly adapted and configured to be contained substantially within the housing, the disc assembly having a cavity for engaging the elongated drive shaft, when the brake assembly is in an engaged state, the disc assembly creates a housing frictional link with the friction material of the brake housing; a release plate assembly having a friction material, the disc assembly being intermediate the release plate assembly and the brake housing, when the brake assembly is in the engaged state, the release plate assembly creates a release plate frictional link with the disc assembly; and a fixed field assembly adjacent the release plate assembly, the fixed field assembly having a coil assembly for creating a magnetic field to attract the release plate assembly thereto when the brake assembly is in a disengaged state, the fixed field assembly having a plurality of biasing members to exert a force against the release plate assembly to create the housing and release plate frictional links.
In still another embodiment, a hub assembly is provided for creating frictional linking with a first adjacent component and a second adjacent component, the hub assembly including a body portion for coupling to a drive shaft, the body portion having a coupling mechanism for supporting a ring assembly to allow for axial motion thereof; and the ring assembly having a first ring sized and configured to create a first frictional link with the first adjacent component when the first adjacent component is biased against the first ring; and a second ring sized and configured to create a second frictional link with the second adjacent component when the first adjacent component is biased against the first ring.
In another embodiment, an electromagnetic having redundancy is provided for parking and holding a motor with an elongated drive shaft including a housing for mounting the electromagnetic brake to the motor, the housing having a friction surface; a disc assembly having a body portion adapted and configured to be contained within the housing, the disc assembly being axially fixed with respect to the elongated drive shaft and engaged to rotate therewith, and the disc assembly having a flange for receiving a first ring and a second ring, each ring slideably engaged to the flange for motion in an axial direction, the first ring being adjacent to the friction surface of the housing; a first release plate having a friction surface; a second release plate having a friction surface, wherein the first and second release plates are free to move in an axial direction, each release plate being adjacent to the second ring; and a fixed field cup having an electromagnetic coil for creating an magnetic field when current flows therethrough; and a plurality of springs to bias the first and second release plates against the second ring, wherein the adjustment cap varies a compression of at least two of the plurality of springs; and a plurality of o-rings in a face of the fixed field cup, wherein when no current flows through the electromagnetic coil, at least one of the release plates is biased against the second ring, the second ring translates a force of the plurality of springs to the first ring thereby engaging the friction surface of the housing to park and hold the elongated drive shaft, wherein when current flows through the electromagnetic coil, the first and second release plates are drawn to the face of the fixed field cup and compress the o-rings, wherein the o-rings facilitate quiet operation of the elevator car brake.
In yet another embodiment, an electromagnetic brake assembly is provided including a disc assembly for engaging an elongated drive shaft of a motor, the disc assembly having a body portion defining a cavity for coupling the body portion to the elongated drive shaft, the body portion having an upstanding flange which defines a plurality of holes; a pair of rings; and a plurality of pin assemblies disposed in the plurality of holes of the upstanding flange for coupling the pair of rings thereto, wherein when the body portion is coupled to the elongated drive shaft, the body portion is axially fixed and the pair of rings move freely in an axial direction.
In still another embodiment, a brake assembly is provided including a field assembly for selectively moving an adjacent plate assembly along an axis between an engaged position and a disengaged position, the field assembly having a cup having a front face and a rear face, the front face defining a channel, a plurality of bores and a plurality of counterbores; a coil secured within the channel for generating a magnetic field to attract the adjacent plate assembly towards the front face of the cup; a plurality of o-rings for cushioning a motion of the adjacent plate assembly towards the front face and for applying a first biasing force to the adjacent plate assembly away from the front face, each of the plurality of o-rings located within one of the plurality of counterbores; and a plurality of springs for applying a second biasing force to the adjacent plate assembly, each spring located within one of the plurality of bores wherein when current flows through the coil, the adjacent plate assembly overcomes the first and second biasing forces, moves closer to the front face and compresses the plurality of o-rings and when no current flows, the first and second biasing forces move the adjacent plate assembly away from the front face.
In another embodiment, an electromagnetic brake assembly is provided including a housing assembly, a release plate assembly, a field assembly and an inductive proximity sensor assembly, the inductive proximity sensor assembly having a nonmagnetic insert integral with the release plate assembly for isolating an area from magnetic flux generated by the field assembly; and an inductive gauge for generating a signal based upon a position of the non-magnetic insert.
In still another embodiment, an electromagnetic brake includes a fixed field assembly for generating a magnetic field; a biasing assembly for generating a non-linear force, the biasing assembly being integral with the field assembly; a release plate assembly adapted and configured for axial motion, the release plate being adjacent to the fixed field assembly; a disc assembly for engaging an elongated drive shaft, the disc assembly being adjacent to the release plate assembly; and a housing assembly for engaging the disc assembly, the housing assembly sized and configured to couple to the fixed field assembly such that a gap surrounds the disc assembly when the magnetic field attracts the release plate assembly against the fixed field assembly, wherein when the magnetic field degrades, the biasing assembly quietly moves the release plate assembly against the disc assembly to cause a frictional linking with the housing assembly.
These and other unique features of the system disclosed herein will become more readily apparent from the following description, the accompanying drawings and the appended claims.